Dampening mechanism for printing presses



Dec. 7, 1937. .B. D. STEVENS DAMPENING MECHANISM FOR PRINTING PRESSES Filed May 20, 1936 2 She ets-Sheet 1 I BWZZZSZeUerza gymda .7

Dec. 7, 1937. D. STEV ENS DAMPENING MECHANISM FOR PRINTING PRESSES 2 Sheets-Sheet 2 Filed May 20, 1936 \lllllllllllllTlfm lllllIlllllllllllll gllll kg???" u l l my l l gmnmumu Patented Dec. 7, 1937 UNITED STATES DAMPENING MECHANISM FOR PRINTING PRESSE Burt D. Stevens, Chicago, Ill., assignor to Miehle Printing Press 8: Manufacturing Company, Chlcago, Ill., a corporatio n of Illinois Application May 20, 1936, Serial No. 80,700

21 Claims.

The invention relates to dampening mechanism for lithographic, printing and other reproducing apparatus and is illustrated in mechanism for selectively controlling the supply of moisture to the plate cylinder of a lithographic offset press.

For satisfactory printing, especially in offset lithography, it is necessary to adequately dampen the printing member to prevent the ink from adhering to those portions of the member which are free of printing areas. Although the entire non-design surface of the member must be supplied with moisture, certain portions require more or less moisture than other portions. It is also well known that better resultsare secured if the water supply, and indirectly, the printing plate are kept cool. This is especially desirable in the sunnner and therefore it has been customary to keep ice in the water fountain to maintain the water at a low temperature.

Apparatus heretofore most commonly used for. supplying moisture to planographic printing plates consists essentiallyof a water fountain, a fountain roller, a ductor roller and water distributing or dampening rollers which have contact with the surface of the printing plate, being intermittently supplied with the required volume of moisture by means of the ductor roller alternately contacting with the fountain roller and with the dampening rollers. This apparatus, however, has not been entirely satisfactory for a number of reasons. One fault which may be mentioned by way of example is the inability to maintain the water fountain clean and free of ink since owing tothe contact of the dampening rollers with the printing plate a certain amount of ink is picked up by these rollers and eventually transferred to the fountain roller. In time the molleton material with which the dampening rollers are covered becomes saturated and clogged with ink, necessitating frequent interruptions in the printing operations.

The primary object of the present invention resides in the provision of improved mechanism forsupplying moisture to planographic printing plates which will overcome the major defects in apparatus heretofore used, which will be simple and compact in construction, economical vto manufacture, and which can be applied to presses now in use.

Another object of the invention is to provide dampening mechanism that will operate efiiciently to maintain an adequate supply of moisture on the printing member and which will be thoroughly diffused over the non-designed surface thereof toproduce the most perfect printing results.

A further object is to provide dampening mechanism having regulating means for controlling the speed of operation of the same so that the supply of moisture to the printing member can be varied to suit conditions.

Another object resides in the provision of dampening mechanism that will supply a controllable quantity of moisture to planographic printing members and which may be uniformly distributed over the entire width of the printing member or varied in amount locally to suit the particular requirements of certain areas on the member without adversely affecting adjacent areas.

A further object is to provide dampening mechanism having means for locally varying the supply of moisture to the printing member and which may be operated in a manner to cool the moisture, thereby rendering the same more effective in repelling ink.

A more specific object is to provide mechanism for supplying moisture to a planographic printing member that will embody a movable moisture absorbing medium and air jets extending the width of the medium for locally controlling the quantity of moisture supplied by the same and which air jets can be. operated to evaporate some of the water from the medium, thereby reducing the temperature of the moisture eventually supplied to the printing member.

Another object is to provide dampening mechanism which will maintain the water in the fountain clean and free of ink.

Still another object is toprovide apparatus of the type described that will permit easy removal of the moisture absorbing medium for cleaning purposes or repair and which can be readily replaced bya new absorbing medium or one that has been laundered.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the device and whereinlike reference characters are used to, designate like parts Figure 1 is a vertical sectional view showing dampening apparatus constructed in accordance with the invention and illustrating its association with a printing cylinder; and

Figure 2 is an elevational view of the dampening mechanism showing the means for imparting movement to the moisture absorbing band.

Referringto the drawings, l0 indicates a plate carrying cylinder of the press having a printing plate mounted thereon in the usual manner. In contact with the printing plate [I are dampening rollers 2, I2, preferably covered with molleton and which in turn contact a distributing roller 4 generally mounted for axial reciprocation. The plate cylinder I0 is rotated by means forming part of the printing press and is suitably inked by inking rollers, which structure is not shown asthe same does not concern the invention.

The dampening mechanism for supplying moisture to the distributing roller M, which is applied to the printing plate II by the dampening rollers 2, consists of any suitable frame structure l5 supporting a water fountain l6 having a drain Each side member II! of the water fountain is formed with an internal diagonal groove by the spaced ribs 20 in which is adapted to ride the ends of a supply roller 2| having wound thereon a relatively long length of cloth such as cheese cloth, muslin or other moisture absorbing material. The cloth band wound on the roller 2| is at all times partly immersed in a liquid such as water in the fountain IS. The liquid is absorbed by the cloth wound on the roller and the same is therefore maintained'in a saturated condition. 7

From the roller 2| the cloth 22 travels upwardly into contact with roller M. It will be noted that the cloth band is taken off of roller 2| on the left thereof, Figure 1, and therefore the band leaving the roller has just been immersed in the liquid in the fountain and is in a saturated condition. Moisture will therefore be supplied to the roller l4 due to the physical contact of the cloth band with the roller. From roller l4 the cloth continues upwardly and passes over a knurled driving cylinder23. Frame members 24 suitably supported by the structure l5 are each formed with an internal diagonal groove by the spaced ribs 25 providing a journal bearing for the respective ends of the upper supporting roller 26 onto which the cloth band 22 is wound. The lower end of the groove formed by ribs 25 is located adjacent the periphery of cylinder 23 and roller 26 has a diameter sufliciently large so as to contact the cylinder when the ends of the same are positioned at the bottom of the respective grooves. As a result of this peripheral contact between roller 26 and the cylinder 23 the former is rotated by the latter and the cloth band is accordingly Wound on the roller 26. As the cloth is removed from the roller 2| the roller will gradually seek a lower level in the fountain I6 and with respect to roller 26 the converse is true as the cloth is gradually wound on this roller, increasing its size and causing the roller to ride upwardly in the grooves 25. The particular mounting for the rollers permitting bodily movement thereof takes care of the gradual decrease in the cloth on the supply roller and the resulting increase on the upper supporting roller.

The driving cylinder 23, as shown in Figure 2, is rotatably mounted on a sleeve 2'! extending between the members 24, there being mounted between the driving cylinder and said sleeve antifriction bearings 28. Extending within the sleeve and projecting beyond the members 24 is a driving shaft 30 having fixedly secured to its right hand end the gear 3|. Said shaft is driven through gear 3| by the gear 32 operatively connecting with and being rotated by the press or by an independent source of power such as an electric motor. The left hand end of shaft 30 connects with and drives speed reducing mechanism housed within the gear box 33, which mechanism can be adjusted by member 34. By a particular adjustment of said member the gear 35 can be rotated at a desired speed. Said gear meshes with a pinion 36 fixed to shaft 31 journalled by the support 38. The other end of the shaft 31 extends through the left hand member 24 and has fixed thereto the gear 38 which meshes with gear 40 carried by the driving cylinder 23.

From the foregoing it will be seen that the driving cylinder is rotated by driving shaft 30 to cause movemeht of-the cloth band and that the speed of the cloth band may be varied by adjustment of member 34.

For manually rotating the driving cylinder ahand crank 4| is provided which may be operatively connected to the end of shaft 42 journalled in the yoke 43. Secured to said shaft is a pinion 44 meshing with a gear 35 of the speed reducing mechanism. Extending the width of the cloth band 22 to the side of said band opposite roller I4 is an air supply pipe 45 suitably supported from one of the members 24 by the bracket 46. A plurality of air jets 41 extend diagonally from said air supply pipe in a direction toward the cloth band and each air jet carries at its end a nozzle 48 which is accordingly positioned in close proximity to the band and immediately below the point of contact of the band with roller 4. Each of the air jets is provided with a regulating valve 50 by which the blast of air delivered from nozzle 48 can be. controlled to suit conditions.

In the operation of the dampening mechanism above described the cloth band 22 will be unwound from supply roller 2| and wound onto the upper supporting roller 26. In travelling upwardly the band is brought into contactwith the periphery of roller M which is suitably driven by the press and thus the moisture supplied by the ban-d will be delivered to the dampening rollers l2 and by these rollers to the printing plate II. By varying the speed of the driving cylinder 23 the speed of movement of the cloth band can be varied. The amount of moisture supplied to roller I4 is largely dependent on the time required for the cloth to travel from its point of immersion in the fountain I6 to the roller. Therefore, as the speed of the band is increased a greater amount of moisture is supplied to roller 4 and the converse is true when the speed of the band is diminished. The amount of moisture supplied by the band can also be varied by the air jets and in particular, local variation of the quantity of moisture is possible. The air blasts from the jets are directed against the cloth band at a point immediately below the contact of the band with the distributing roller I4. The moisture in the band is reduced by the action of the air blasts and as the jets extend for the width of the band in spaced relation, it is possible by adjustment ,of the valves 50 to locally vary the quantity of moisture supplied by the band so as to suit the particular requirements of certain areas on the printing member which may require more or less moisture than other areas. Variation in the intensity of the air blasts directed against the cloth band enables the operator to selectively control not only the quantity of moisture supplied by the band but also the temperature of said moisture. This is possible as the air blasts will evaporate some of the moisture from the cloth band, thereby reducing the temperature of the moisture re-' maining and which is eventually supplied to the printing plate. In this connection, it is possible to speed up the travel of the cloth band so that the quantity of moisture which would be supplied to the roller I4 is in excess of the requirements of the printing member and by adjustment of the air jets the excess can be evaporated to thereby reduce the temperature of the remaining moisture. By keeping the temperature of the moisture as low as possible, especially in the summer time, its effectiveness in repelling ink is increased.

By using a relatively long band that has movement only in one direction, namely, from the fountain to the takeup roller, a high degree of cleanliness in the water supply is possible. Although some ink maybe taken up by the band this does notreach the fountain and thus the water in the fountain is not contaminated as was heretofore the case. Also the band wipes the surface of the roller H since the roller has a surface speed far greater than the movement of the band, and it will be noted that the band passes from the cylinder 23 to the underside of the roller 26. The band is thus wound on the roller with the surface that contacted roller H directed inwardly. This is an important feature as it enables extended use of the cloth band since the same can be reversed, that is, with roller 26 in the fountain, whereby the opposite surface of the band will be caused to contact the distributing roller. The band when entirely wound upon the upper supporting roller can be used again as described, or the band can be laundered and a new band or one that has been laundered substituted in its place.

The mounting of the fountain roller within guides, allowing bodily movement thereof, permits the roll of cloth to always rest on the bottom of the fountain so that the roll, and particularly that portion of the band being unwound from the roller, is in a saturated condition irrespective of the quantity of water there may be in the container. Also the resting of the roll of cloth on the bottom of the fountain supplies the necessary braking eifect on the roller to maintain the band under tension. This tension is substantially uniform and is automatically applied by the contact which the roll of cloth has with the bottom of the fountain. As a result of this tensiorgm the cloth band proper contact is made with the distributing roller as all tendencies for wrinkles to form on the cloth while the same contacts with the distributing roller are eliminated. v

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings, as various other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the' scope of the claims.

I claim:

1. In a dampening device, a distributing roller, a movable moisture absorbing medium in contact with said roller,.said medium having movemm in one direction only from a source of liquid supply to a point of takeup, and means directing a blast of air against said medium in advanceof its contact with said roller.

2. In a dampening device, a distributing roller, a movable moisture absorbing, medium in contact with said roller, said medium having-movement in one direction only from a source of liquid supply to a point of takeup, and a plurality of means extending the width of the medium, each directing a blast of air against said medium in advance of its contact with said roller.

3. In a dampening device, a distributing roller, a movable moisture absorbing medium in contact with said roller, supporting members for the respective ends of said medium whereby the same is unwound from one of thesupporting members and wound on the other, and means extending the width of said medium directing a blast of air against the same in advance of its contact with said roller.

4. In a dampening device, a distributing roller, a movable moisture absorbing medium in contact with said roller, supporting members for the respective ends of said medium whereby the same is unwound from one of the supporting members and wound on the other, and a plurality of spaced means extending the width of said medium, each of said means directing a blast of air against the medium in advance of its contact with said roller.

5. In a dampening device, a distributing roller, a movable moisture absorbing medium in contact with said roller, said medium having movement in one direction only from a source of liquid supply to a point of takeup, means imparting said movement to the medium and having adjustability to vary the speed of said movement, and a plurality of spaced means extending the entire width of said medium, each of said means directing a blast of air against the medium in advance of its contact with said roller.

6.' In a dampening device, a distributing roller, a movable moisture absorbing medium in contact with said roller, said medium having movement in one direction only from a source of liquid supply, to a point of takeup, an adjust able drive for imparting said movement to the" parting movement to said medium to cause winding of the same on its supporting member, and a plurality of spaced means extending the errtire width of said medium, each of-said means directing a blast of air against the medium in advance of its contact with said roller.

8. In a dampening device, a distributing roller, is movable moisture absorbing medium in contact with said ,roller, supporting members for the respective ends of said medium whereby the same is unwound from one of the supporting members and wound on theother, .a drive for winding said medium on its Supporting member, a plurality of air jets extending the entire width of .said medium, each of said Jets directing a blast of air against the medium in advance of its contact'with said roller, and a valve for'each of said air jets;

9. In a dampening device, a distributing roller, a moisture absorbing band in contact with said roller, members above and below the distributing roller respectively for supporting the ends of said band, a drive for winding said band onto one of said members and unwinding the band from the other of said members, a fountain journalling the member having the band unwinding therefrom, and a plurality of adjustable means each directing a blast of air against said band in advance of its contact with said roller.

10. In a dampening device, a distributing roller, a moisture absorbing band in contact with said roller, members above and below the distributing roller respectively for supporting the ends of said band, a drive for winding said band onto one of said members and unwinding the band from the other of said members, a fountain journalling the member having the band unwinding therefrom, and a plurality of air jets extending the entire width of said band, each of said jets directing a blast of air against the band in advance of its contact with said rollers.

11. In a dampening device, a distributing roller, a moisture absorbing band in contact with said roller, members above and below the distributing roller respectively for supporting the ends of said band, a drive for winding said band onto one of said members and unwinding the band from the other of said members, a fountain journalling the member having the band unwinding therefrom, a plurality of spaced air jets extending the entire width of said band,

each of said jets directing a blast of air against ,the band in advance of its contact with said roller, and a valve for each air jet.

12. -In a dampening device, a distributing roller, a fountain located below said roller and supporting a supply roller having a band of water absorbing material wound thereon, a driving cylinder located above said distributing roller and having contact with the band for unwinding the same from said supply roller, said band contacting the distributing roller intermediate the fountain and driving cylinder, means rotated by said driving cylinder for winding the band received therefrom, and a plurality of spaced air jets extending the width of said band, each of said air jets directing a blast of air against the band in advance of its contact with said distributing roller.

13. In a dampening device, a distributing roller, a fountain located below said roller and supporting a supply roller having a band of water absorbing material wound thereon, a driving cylinder located above said distributing roller and having contact with the band for unwinding the same from said supply roller, said band contacting the distributing roller intermediate the fountain and driving cylinder, means rotated' by said driving cylinder for winding the band received therefrom, said cylinder and winding means for said band being constructed and arranged so that the band is wound on said means with that surface which'had contact with the distributing roller directed inwardly, and a plurality of spaced air jets extending the entire width of the band, each of said air jets directing a blast of air against the band in advance of its contact with said distributing roller.

14. In a dampening device, a distributing roller, a fountain located below said roller and Journailing a supply roller having a relatively long cloth band wound thereon, a driving cylinder located above the distributing roller and having contact with the band for unwinding the same from said supply roller, said band contacting the aromas periphery of the distributing roller intermediate the fountain and driving cylinder, means for varying the speed of said driving cylinder, a takeup roller rotated by said driving cylinder for winding the cloth band received therefrom, a plurality of air jets extending the entire width of said band, each of said jets directing a blast of air against the band in advance of its contact with said distributing roller, and a valve for'each of said air jets.

15. In a dampening device for lithographic presses, a distributing roller having a surface speed equal to the surface speed of the lithographic plate, a movable moisture carrying medium contacting said roller for supplying moisture thereto, saidmediumhavingmovementinone direction only from a source of liquid supply to a point of take-up, and means driving said moisture carrying medium at variable speeds so as to supply variable amounts of moisture to the distributing roller.

16. In a dampening device for lithographic presses, a distributing roller having a surface speed equal to the surface speed of the lithographic plate, a movable moisture carrying medium contacting said roller for supplying moisture thereto,sa.id medium having movement in one direction only from a source of liquid supply to a point of take-up, and means driving said moisture carrying medium at variable speeds, whereby said medium can be driven at a speed to supply only the necessary moisture to said roller or at a greater speed to supply slightly excess moisture to the distributing roller.

17. In a dampening device for lithographic presses, a distributing roller having a surface speed equal to the surface speed of the lithographic plate, a movable moisture carrying medium contacting said roller for supply moisture .having contact with said roller for supplying moisture thereto, said band having a speed less than the surface speed of said roller, whereby said band has a wiping action on the surface of the roller so that any particles of ink that may be carried from the lithographic plate to the distributing roller are removed therefrom by said band.

19. In a dampening device, a distributing roiler, a fountain located below said roller, said fountain joumalling' a supporting member having a band of water absorbing material wound thereon, said journalling means mounting the supporting member so that the band of material thereon is always in contact with the bottom of said fountain, a second supporting member located above the roller and having said band wound thereon, said band contacting the distributing roller intermediate the supporting members, and means driving 'the second supporting member at variable speeds.

20. In a dampening device, a distributing roller, a movable moisture absorbing band in contact with said roller, supporting members for the respective ends of said band so that the same is unwound from one of the supporting members and wound on the other,-a fountain journalling the supporting member from which said band is unwound and. permitting the roll thereon to rest on the bottom of the fountain, whereby a braking eflect is produced to maintain tension on the band between the supporting members.

21. In a dampening device, a distributing roller, a movable moisture absorbing band in con- 10 tact with said roller, members above and below the distributing roller respectively for supporting the ends of the band, a drive for winding said band onto one of said members and unwinding the band from the other of said members, and a fountain journalling the member having the band unwinding therefrom, said journalling means permitting bodily movement of the memher in a substantially vertical direction.

' BURT n. STEVENS. 

